1. Technical Field
The present invention relates to microorganism mixtures and microorganisms for use in the measurement of environmental factors. Simple and highly accurate measurement of environmental factors becomes possible by using the microorganism mixtures or microorganisms of the invention.
2. Prior Art
Any organism, irrespective of being a microorganism, animal or plant, is equipped with mechanisms for sensing minute changes or specific chemical substances in the external environment. Specifically, sensors specific to individual factors present on the surfaces of cell membranes or inside of cells percept the presence (or changes) of those factors, transfer that information to the promoters of relevant genes through transcription regulatory factors, and switch on or off the expression of the target genes. Thus, organisms cope with environmental changes. Recent advances in molecular biology have elucidated a large number of sensor proteins of procaryotes and eucaryotes involved in perception of external environment, as well as transcription regulatory factors functioning downstream of these proteins and promoter sequences of the target genes of such factors. These sensor proteins include proteins that detect changes in physicochemical states such as oxygen level or osmotic pressure; proteins that percepts the presence or absence of specific substances such as phosphate ions, nitrate ions or heavy metal ions; and proteins that sense such substances as hormones occurring in nature only in extremely small quantities. On the other hand, identification of genes involved in the synthesis of hormones exhibiting physiological activity in extremely small quantities has also progressed.
It is believed that plants have evolved diversified perception systems for external environment because they are organisms unable to immigrate. Actually, it is presumed that plants have several hundred environmental sensor genes according to information about the genome of Arabidopsis thaliana. It is expected that the entire picture of the potential sensing functions plants have will be elucidated at the molecular level in near future.